Traditionally, for the bristle cluster of a toothbrush, substantially cylindrical tooth cleaning bristles are used, circular cylindrical bristles, in particular, but also cylindrical shapes having bases which are different from the circular shape, being known. Besides cylindrical tooth cleaning bristles of triangular, square or polygonal cross sections, tooth cleaning bristles having complicated contours on the outer surface have also recently been proposed, e.g. tooth cleaning bristles of star-shaped or cruciform cross sections.
U.S. Pat. No. 3,302,230 shows a toothbrush having bristles which taper in the longitudinal direction and which are designed to be of triangular, star-shaped or rhombic configuration in cross section in order to obtain a scraping effect with the outer surface contoured edges and to achieve an improved adhesion of the toothpaste compared to circular cross sections. JP 6-233709 A also proposes such angular cross-sectional contours for the tooth cleaning bristles of a toothbrush in order to effect better plaque removal by virtue of the outer surface edges and their scraping effect. DE 195 33 815 A1 proposes, on the other hand, a toothbrush whose bristles, on their outer surface, are designed to have a single-turn or multi-turn helix in order to obtain an enhanced massaging effect. Such helically twisted contours have the drawback, however, that the bristles can easily catch amongst themselves and, moreover, that penetration into interdental spaces is made more difficult, since the bristles would need to twist for this purpose.
From DE 198 18 345 A1, multilayered tooth cleaning bristles of non-homogeneous material cross section are known, in which a relatively hard plastic core is designed to be encased in an elastomeric plastic layer contoured by stamping against the core, longitudinal ribs which are distributed over the periphery and which give the bristle an altogether approximately flower-shaped cross section, or hole-shaped recesses in the outer surface, being proposed as the contouring. Such multilayered bristles are, however, complicated to produce and correspondingly expensive and, moreover, are only conditionally suited to fastening by the so-called anchor-plugging method. In order to increase the flexural rigidity of even long, very narrow bristles, DE 1 997 717 proposes constructing a bristle from a plurality of filaments which are bonded together along their longitudinally running contact surfaces, whereupon convexly curved longitudinal ribs are formed on the outer surface in the style of a flower stem bunch. Between the filaments forming the bristle, storage pockets are formed, in which moisture collects. Self-evidently, this bristle, too, which is bonded together from a plurality of filaments, is produced by complex means. In U.S. Pat. No. 5,533,227, a toothbrush is additionally described, the bristles of which are sharpened to a point at the bristle ends. Apart from these sharpenings, the bristles are, however, of circular cylindrical configuration.
Other bristles having outer surface contours for other purposes, however, are shown by the publications EP 0 329 505 B1, DE 11 40 901, U.S. Pat. No. 5,725,954, U.S. Pat. No. 2,434,533 and GB 1,137,407.